Study of structural,electromagnetic and dielectric properties of cadmium substituted Ni–Zn nanosized ferrites

Sol-gel auto-combustion method was adopted to prepare Cd²⁺ ions substituted Ni–Zn nanosized ferrites having a chemical formula Ni_0.5Zn_0.5-xCd_xFe₂O₄ (0.0 $\le x\le 0.4)$. Their structural, electromagnetic, and dielectric properties were investigated by using XRD, FE-SEM, EDS, FTIR, VSM, and IS. The XRD analysis revealed a single-phase cubic structure of all samples. The addition of cadmium increased the lattice constant and cell volume of Ni–Zn ferrite due to the difference in the ionic radii between Cadmium (0.97 ?Å) and Zinc (0.74 ?Å). FESEM images showed irregularly shaped grain sizes in the range of 40 to 73 ?nm with random orientations and some agglomeration. The FTIR analysis also confirmed the presence of spinal ferrite phase functional groups in all samples. The saturation magnetization decreased (from 89.51 to 71.32 emu/g) with increasing cadmium content. However, the remanent magnetization and coercivity parameters increased with an increase in cadmium content. The dc resistivity as a function of the temperature of all samples was investigated, and the activation energies were found to be in the range of 0.48 to 0.51 ?eV. The dielectric loss decreased with increasing cadmium content. However, the dielectric constant and dielectric loss tangent (tan) varied non-monotonically with increased cadmium content.     

Tuning the morphological properties of cellulose aerogels: an investigation of salt-mediated preparation

Cellulose - In this study, alkali and alkaline earth metal chlorides with different cationic radii (LiCl, NaCl, and KCl, MgCl2, and CaCl2) were used to gain insight into the behavior of cellulose...     

Interpretation of the Role of Composition on the Inclusion Efficiency of Monovalent Cations into Cobalt Hexacyanoferrate

Cobalt hexacyanoferrate of various compositions was prepared in flow mode and the role of the vacancy on the structure, thermogravimetric (TG) properties, and the adsorption efficiency was studied. The material, Na_yCo[Fe(CN)₆]_1−x ⋅ z H₂O, with a minimum vacancy of x=0.014 to the highest x=0.47, was obtained. The TG-differential scanning calorimetry (DSC) profile showed a distinct influence of the vacancy on the water release temperature. Materials with x>0.35 showed a smooth release of water at a relatively lower temperature. However, for the materials with x<0.35, water release took place in multiple steps, suggesting the existence of various forms of water. The FTIR profiles supported the existence of free and bonded water molecules. However, the materials with multiple water peaks in the FTIR spectra showed a shift of the major XRD peaks when heated at 285 °C in N₂ atmosphere. Regarding the effect of the vacancy on the adsorption behavior, for NH₄, the adsorption was found to be proportional to the number of Na atoms in the material, confirming the ion-exchange process. On the contrary, the materials with low vacancy and high Na content showed nominal Cs adsorption capacity. Interestingly, the K adsorption capacity was found to be in between that of the other two ions. This means the ionic size decides the rate of placement into the interstitial sites. For larger ions like Cs, the ease of percolation via the vacancy decides the overall adsorption efficiency.     

A Unique Tryptophan C‐Prenyltransferase from the Kawaguchipeptin Biosynthetic Pathway

Cyanobactins are a rapidly growing family of linear and cyclic peptides produced by cyanobacteria. Kawaguchipeptins A and B, two macrocyclic undecapeptides reported earlier from Microcystis aeruginosa NIES‐88, are shown to be products of the cyanobactin biosynthetic pathway. The 9 kb kawaguchipeptin (kgp) gene cluster was identified in a 5.26 Mb draft genome of Microcystis aeruginosa NIES‐88. We verified that this gene cluster is responsible for the production of the kawaguchipeptins through heterologous expression of the kgp gene cluster in Escherichia coli. The KgpF prenyltransferase was overexpressed and was shown to prenylate C‐3 of Trp residues in both linear and cyclic peptides in vitro. Our findings serve to further enhance the structural diversity of cyanobactins to include tryptophan‐prenylated cyclic peptides.     

Recovery of palladium using chemically modified cedar wood powder

Japanese cedar wood powder (CWP) was chemically modified to a tertiary-amine-type adsorbent and studied for the selective recovery of Pd(II) from various industrial waters. Batch adsorption tests performed from 0.1 M to 5 M HCl and HNO₃ systems reveal stable performance with better results in HNO₃ medium. The maximum loading capacity for Pd(II) was studied in HCl as well as in HNO₃. A continuous-flow experiment taking a real industrial solution revealed the feasibility of using modified CWP for the selective uptake and preconcentration of traces of palladium contained in acidic effluents. In addition, stable adsorption performance even on long exposure to γ-irradiation and selective recovery of palladium from simulated high-level liquid waste (HLW) are important outcomes of the study.     

Basicities of some 9-substituted acridine-4-carboxamides: A density functional theory (DFT) calculation

Acid-base properties of drugs are important in understanding the behaviour of these compounds under physiological condition. In order to understand such behaviour the proton affinities of acri-dine 4-carboxamides with substitution (R) at the 9-position are theoretically studied, and considered for the basic sites of both the heterocyclic ring as well as side chain nitrogens. In 9-amino acridine 4-carbox-amide, the -NH₂ group is observed to be an additional basic site. The heterocyclic nitrogen of substituted carboxamides (R =-NH₂, -O-methyl, -O-ethyl, and -O-phenyl) is more basic than the side chain nitrogen, however, side chain nitrogen corresponds to more basic site for some carboxamides (R = -OH and-Cl) and the -NH₂ group represents the least basic site of 9-amino acridine 4-carboxamide. In addition to presenting the basicities of these drugs an indication of another hydrogen-bond between heterocyclic ring N and carboxamide chain O is observed. The difference of basicities with substituents at 9-position are very narrow and carboxamides with substituents at 9-position are found to be suitable for studying intramolecular H-bonds between the heterocyclic N and carboxamide O. The resultant stabilization of a configuration due to such H-bonding is determined     

In vitro hydrolytic degradation of poly(?-caprolactone) grafted dextran fibers and films

We studied the hydrolytic degradation of poly(?-caprolactone) grafted dextran (PGD) fibers and films (matrices) prepared by electrospinning and solvent evaporation methods, respectively. In vitro degradation and erosion experiments were carried out in phosphate buffered saline (pH 7.4 ± 0.1) at 37 ± 1 °C for 150 days. Changes in molecular weights and morphologies of the PGD matrices were monitored as a function of degradation time. The extent of degradation was measured by physical weight loss, scanning electron microscopic (SEM) observations, Fourier transform-infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). During the progress of hydrolysis, GPC chromatograms appeared bi modal for fibers and bi and trimodal for the films. The crystallization temperature (T_c) and heat of fusion were significantly increased in both matrices; this indicated preferential hydrolytic degradation in amorphous regions followed by cleavage-induced crystallization. The biodegradation rates were faster for the films (28%) than fibers (23%). After 150 days of degradation, the pH was steady at 5.8 ± 0.3 for fibers and 6.1 ± 0.3 for films. The faster degradation of the films could be probably due to autocatalysis in the interior of the films and the degraded oligomers are hard to diffuse out into the surrounding solution due to its compact physical geometry. Thus, our preliminary results about the degradation of matrices suggested that PGD nanofibers could be excellent matrices in tissue engineering over the films.     

Interference of ascorbic acid in the sensitive detection of dopamine by a nonoxidative sensing approach

The electrochemistry of a poly(anilineboronic acid)/carbon nanotube composite was studied in the presence of dopamine and ascorbic acid. To understand the binding affinity of dopamine and ascorbic acid to the boronic acid functional groups in the composite, the association constants between the diol groups in dopamine and ascorbic acid and the boronic acid were experimentally determined using a fluorescence-based binding assay. The results demonstrate that ascorbic acid could severely interfere with the detection of dopamine in nonoxidative boronic acid-binding approaches: Ascorbic acid was able to electrocatalytically reduce the fully oxidized polyaniline backbone during the electrochemical oxidation process; similarly to dopamine, ascorbic acid was also able to bind to the boronic acid groups through its planar diol group even though the binding affinity is much lower. The examination of the dopamine transduction mechanism and ascorbic acid interference mechanism in this nonoxidative approach will benefit the design of future boronic acid-based sensors.